This section contains the pre-requisites of leaving Western Ghats in Uncharted: Lost Legacy. The area is visited as a part of a chapter called "Western Ghats" and gaining access to the exit enables you to begin the fifth chapter of the game.
Your main objective in the region is to visit three main fortresses (Parashurama's, Shiva's, and Ganesha's), each ending with a riddle that involves rotating rings creating a symbol when correctly aligned. Completing each riddle unlocks a single waterfall at the gates of Halebid. The gate itself is found in the north-western part of the map and is shown on the screenshot above.
If you've unlocked all three waterfalls, interact with the rotating mechanism found at the gates of Halebid to unlock access to the area and begin the fifth chapter (make sure to complete all unfinished side activities, as proceeding to the next chapter will force you to begin these activities from scratch)